On August 15 1998 Northern Ireland’s fragile peace was shattered when a dissident republican car bomb ripped through the Co Tyrone market town of Omagh.

The attack, which came four months after the signing of the Belfast Agreement, was the single deadliest atrocity in the history of the Troubles. This is a timeline of the main events leading up to and beyond the Real IRA bomb explosion, which claimed the lives of 29 people, including a woman pregnant with twins.

The same car, now carrying the fake Northern Ireland reg, MDZ 5211, is driven into Market Street, Omagh, and parked outside SD Kells clothes shop. Two male occupants are seen walking away in the direction of Campsie Road.

Samaritans office in Coleraine called with another warning. “Am I through to Omagh? This is a bomb warning. It’s going to go off in 30 minutes.”

Caller said bomb was 200 yards from courthouse. He also gave codeword “Martha Pope”.

14.35pm

UTV receives another phone warning: “Bomb, Omagh town, 15 minutes.” Two of these warnings were phoned from a call box in Forkhill, south Armagh. The third was made from a phone box in Newtownhamilton, also in south Armagh.

2.31pm to 3.10pm

UTV and Samaritans both place emergency calls to the Royal Ulster Constabulary control centre. Message immediately passed to officers in Omagh and evacuation operation commences. There was no street named Main Street in Omagh. The only target specified was the courthouse, which was at the top of High Street at the west end of the town. The car had actually been parked at the east end of the town, on Market Street, more than 500 yards from the court. Police cordon off High Street and move shoppers and shop owners down to Market Street before commencing a search round the courthouse.

As a result all the people who had been in Omagh town centre when the warning came through had now assembled in Market Street, yards from the red Cavalier. Among those gathered was a group of Spanish students who were spending the summer in Buncrana. They had gone to

Omagh for the day along with a number of local children from the Co Donegal town.

3.10pm

A 500lb bomb packed in the Cavalier is detonated with a remote trigger. The explosion tears through Market Street. Shop fronts on both sides are blown back on top of customers still inside. Glass, masonry and metal tears through the crowd on the street as a fireball sweeps out from the epicentre. Twenty-one people are killed instantly - some of their bodies were never found, such was the force of the blast. A water main under the road ruptures. Gallons of water gushes out. Some of the dead and badly injured are washed down the hill.

3.10pm

Emergency operation begins. The two ambulance crews on call at the nearby Tyrone County Hospital arrive at the scene within minutes. Survivors are already tending to the injured and covering the dead. Civilians who had been on nearby streets also rush to the scene to help. People grab medical supplies from a chemist’s shop while linen from a drapers is used to cover the victims.

Buses are commandeered from the nearby Ulsterbus station to help take the injured to hospital. Shelves and doors are used as makeshift stretchers. As news of the attack filters through, off-duty medical personnel head for the hospital. As well as those who died, more than 300 people were injured in the blast. Army helicopters are scrambled to help the ambulance service ferry patients from the swamped Tyrone hospital to other medical centres.

Omagh’s leisure centre is transformed into an incident centre, with hundreds of relatives gathering there waiting for news on loved ones. Inundated with calls, the Tyrone County Hospital phone system crashes. Staff ask members of the public for mobile phones to contact other hospitals. A temporary morgue is set up in a British Army base in the town.

Sunday August 16th

Relatives of those people still unaccounted for wait at the leisure centre overnight.

Noon

The identity of the 28th victim who died on the day is revealed. (Sixty-one-year Sean McGrath would die a month later from injuries sustained in the bomb.)

12.45pm

The then RUC chief constable Ronnie Flanagan addresses the world’s press at the scene. “This is an attack, not carried out against the police or the army, but against the people of Omagh. We have had men, women and children slaughtered, slaughtered by murderers who want to murder, slaughtered by murderers who have nothing else to offer but murder, people who gave us a totally inaccurate warning, people who phoned to say there was a bomb close to the courthouse and as our officers searched and moved people from the area of the courthouse, a bomb detonated some 400 yards away.”

An ambulance carrying one of the injured from the Erne hospital to Belfast collides with a car. The car’s driver, 38-year-old father-of-three Gary White, is killed.

The Real IRA admits responsibility for the attack. The group claims its target was commercial and not civilian and blames loss of life on failure of RUC to respond to “clear” warnings. Northern Ireland Secretary Mo Mowlam describes the statement as “a pathetic excuse for mass murder”.

Saturday August 22nd

One week after the attack a day of reflection is held. An estimated 60,000 people gather in Omagh with thousands more attending vigils in other towns and cities across Ireland.

In Omagh, a service is conducted by church leaders on the steps of the courthouse. The event is best remembered for a moving performance by local singer Juliet Turner, whose ballad Broken Things was beamed across the world.